I took your advice and its not working ... I do this in
onSurfaceChanged()
center = Object3D.createDummyObj();
center.translate(sol[0].getTransformedCenter());
center.build();
earth[0].translate(0, 50, 0);
earth[0].setTexture("texture");
earth[0].addChild(center);
and in onDrawFrame()
center.rotateY(1f);
but nothing happends ... whats am I doing wrong?? the sol and earth objects are loaded obj models.